The present invention relates to a weight selecting apparatus for automatically measuring weights of products and other articles in the various industrial fields of medicines, chemicals, foods and the like; inspecting whether or not the weight of each of the objects to be inspected is within a specific weight range; and selecting the objects into non-defective ones and defective ones. In particular, the present invention relates to a weight selecting apparatus capable of automatically performing, at specific intervals, a calibrating operation of inspecting the accuracy of a weighing unit for performing weight measurement thereby certainly performing inspection at a high reliability, and also relates to a weight selecting apparatus for certainly carrying objects to be inspected with a relatively simple mechanism and performing weight measurement of the objects.
In the various industrial fields, as one of quality control items, it has been performed to measure weights of products and other articles; inspect whether or not the weight of each of the objects to be inspected is within a specific range; and select the objects into non-defective ones and defective ones. In the field of medicines, particularly, weight inspection has been regarded as one of extremely important inspection items. This is because a variation in weight directly leads to a variation in effective content and such a variation in effective content presents a large problem particularly for a medicament with its does required to be strictly managed.
Recently, weights of medicines such as capsules have come to be automatically inspected using a weight selecting apparatus, and as such a weight selecting apparatus there has been known an apparatus shown in FIG. 9.
The weight selecting apparatus shown in FIG. 9, adapted for weight inspection of capsules, includes a hopper xe2x80x9caxe2x80x9d for continuously feeding capsules as objects to be inspected; a magazine xe2x80x9cbxe2x80x9d for feeding the capsules from the hopper xe2x80x9caxe2x80x9d to a weighing base xe2x80x9cgxe2x80x9d one by one; a weighing unit xe2x80x9ccxe2x80x9d for measuring weights of the capsules; an acceptability determining unit (not shown) for determining the acceptability of each capsule on the basis of the measured result; and a selecting/recovering unit xe2x80x9cdxe2x80x9d for selecting the capsules into non-defective ones and defective ones on the basis of the acceptability determination and recovering them.
The hopper xe2x80x9caxe2x80x9d is formed into an approximately funnel shape in which a specific number of capsules are to be stored. As the amount of capsules stored in the hopper xe2x80x9caxe2x80x9d is reduced, new capsules are supplied from a large hopper xe2x80x9cexe2x80x9d shown in FIG. 9, whereby a specific number of capsules are usually stored in the hopper xe2x80x9caxe2x80x9d.
The magazine xe2x80x9cbxe2x80x9d is a vertically movable pipe with its upper end inserted through the hopper xe2x80x9caxe2x80x9d, and a shutter xe2x80x9cfxe2x80x9d for opening/closing a lower end opening portion of the magazine xe2x80x9cbxe2x80x9d is mounted to the lower end portion of the magazine xe2x80x9cbxe2x80x9d. The weighing unit xe2x80x9ccxe2x80x9d includes a V-rail xe2x80x9chxe2x80x9d, having a V-shaped cross section, for guiding each capsule supplied from the magazine xe2x80x9cbxe2x80x9d to a weighing base xe2x80x9cgxe2x80x9d; a pusher xe2x80x9cixe2x80x9d for turning sideways each capsule supplied on the V-rail xe2x80x9chxe2x80x9d and pushing the capsule out of the V-rail xe2x80x9chxe2x80x9d to move it on the weighing base xe2x80x9cgxe2x80x9d; a stopper xe2x80x9cnxe2x80x9d for stopping each capsule moved onto the weighing base xe2x80x9cgxe2x80x9d at a specific position; and an injector xe2x80x9cpxe2x80x9d for moving each capsule from the weighing base xe2x80x9cgxe2x80x9d to the selecting/recovering unit. The selecting/recovering unit xe2x80x9cdxe2x80x9d includes an ejecting chute xe2x80x9cjxe2x80x9d for ejecting each capsule after weight measurement; a defective ejecting chute xe2x80x9ckxe2x80x9d branched from the ejecting chute xe2x80x9cjxe2x80x9d; and a selecting gate xe2x80x9cmxe2x80x9d provided at a branch point where the defective ejecting chute xe2x80x9ckxe2x80x9d is branched from the ejecting chute xe2x80x9cJxe2x80x9d.
The weight inspection using the above weight selecting apparatus is performed as follows:
That is to say, the capsules in the hopper xe2x80x9caxe2x80x9d are charged in the magazine xe2x80x9cbxe2x80x9d in a state being aligned in a row by vertical motion of the magazine xe2x80x9cbxe2x80x9d, and as shown by a broken line in FIG. 9, the shutter xe2x80x9cfxe2x80x9d is temporarily opened when the magazine xe2x80x9cbxe2x80x9d reaches the lowermost point and thereby one of the capsules is discharged from the lower end opening portion of the magazine and is placed on the V-rail xe2x80x9chxe2x80x9d. The pusher xe2x80x9cixe2x80x9d is immediately moved in the horizontal direction to turn sideways the capsule on the V-rail xe2x80x9chxe2x80x9d and move it on the weighing base xe2x80x9cgxe2x80x9d. The moving capsule is stopped by the stopper xe2x80x9cnxe2x80x9d at a specific position on the weighing base xe2x80x9cgxe2x80x9d, followed by weight measurement. After weight measurement, as shown by a broken line in FIG. 9, the stopper xe2x80x9cnxe2x80x9d is moved downward to open a charging port of the ejection chute xe2x80x9cjxe2x80x9d and at the same time the injector xe2x80x9cpxe2x80x9d is moved as shown by an arrow in FIG. 9 to charge the capsule on the weighing base xe2x80x9cgxe2x80x9d into the ejection chute xe2x80x9cjxe2x80x9d of the selecting/recovering unit xe2x80x9cdxe2x80x9d. At this time, the acceptance determining unit (not shown) determines, on the basis of the result of weight measurement, whether or not the weight of the capsule is within a specific range, and opens/closes the selecting gate on the basis of the determined result. In the case where the capsule is determined as a non-defective capsule having a weight being in the specific range, the selecting gate xe2x80x9cmxe2x80x9d closes the port of the defective ejecting chute xe2x80x9ckxe2x80x9d, whereby the non-defective capsule is ejected outside the apparatus through the ejecting chute xe2x80x9cjxe2x80x9d. On the other hand, in the case where the capsule is determined as a defective capsule having a weight being out of the specific range, as shown by a dotted line in the figure, the selecting gate xe2x80x9cmxe2x80x9d is opened and thereby the upper end opening portion of the defective ejecting chute xe2x80x9ckxe2x80x9d is opened and also the selecting gate xe2x80x9cmxe2x80x9d blocks the ejecting chute xe2x80x9cjxe2x80x9d at the branch point between the defective capsule ejecting chute xe2x80x9ckxe2x80x9d and the same to introduce the defective capsule into the defective ejecting chute xe2x80x9ckxe2x80x9d. Thus, the defective capsule is selected and recovered through the defective ejecting chute xe2x80x9ckxe2x80x9d. Thereafter, the above operation is continuously repeated, to thus automatically select the weights of the capsules.
The related art weight selecting apparatus, however, has a disadvantage that a so-called calibration for inspecting and confirming the accuracy of weight measurement by the weighing unit xe2x80x9ccxe2x80x9d must be manually performed each time, and thereby the calibration work is made burdensome.
To be more specific, the xe2x80x9ccalibrationxe2x80x9d is to compare a measuring instrument with a standard (reference) instrument or a standard sample, confirm that an error therebetween is within a reference value, and to adjust and repair the measuring instrument if the error is out of the reference value; and to stably obtain products each having a specific quality, each measuring instrument must be subjected to calibration at a necessary period determined according to the purpose and importance.
In the above-described related art weight selecting apparatus, the calibration is performed by confirming the accuracy of a balance of the weighing unit xe2x80x9ccxe2x80x9d using a reference weight, and adjusting and repairing the balance if an error measured is more than a reference value. However, since such an apparatus is generally configured such that a number of inspection lines composed of measurement mechanisms shown in FIG. 9 are arranged in a plurality of rows (6 rows and 12 rows types, commercially available apparatus) for processing a large amount of capsules for a short time, the calibration must be performed using the reference weight for each line, so that the calibration work takes a large labor. As a result, it is expected to develop a weight selecting apparatus capable of automatically performing the above calibration.
The above-described related art weight selecting apparatus also has a disadvantage that since capsules are carried from the hopper xe2x80x9caxe2x80x9d to the weighing base xe2x80x9cgxe2x80x9d one by one, followed by weight measurement, and the capsules are fed to the selecting/recovering unit xe2x80x9cdxe2x80x9d, the carrying mechanism is complicated.
That is to say, as described above, the related art weight selecting apparatus is configured such that one capsule is discharged from the lower end of the magazine xe2x80x9cbxe2x80x9d and is placed on the V-rail xe2x80x9chxe2x80x9d when the vertically movable magazine xe2x80x9cbxe2x80x9d reaches the lowermost point, and the capsule is turned sideways by the pusher xe2x80x9cixe2x80x9d and at the same time it is moved to the weighing base xe2x80x9cgxe2x80x9d for weight measurement; and directly after weight measurement, the stopper xe2x80x9cnxe2x80x9d is moved to open the charging port of the ejecting chute xe2x80x9cjxe2x80x9d and also the capsule on the weighing base xe2x80x9cgxe2x80x9d is charged into the ejecting chute xe2x80x9cgxe2x80x9d by the injector xe2x80x9cpxe2x80x9d. That is to say, the carrying mechanism for carrying the capsule has a number of moving parts such as the magazine xe2x80x9cbxe2x80x9d, pusher xe2x80x9cixe2x80x9d, stopper xe2x80x9cnxe2x80x9d, injector xe2x80x9cpxe2x80x9d, and the like, and a drive mechanism and a control mechanism for moving these parts at correct timings are required to be provided. In this way, the related art weight selecting mechanism has a very complicated mechanism for carrying capsules, which obstructs the improvement of processing ability and raises the parts cost, assembling cost and the like, and further may cause a failure in the carrying step such as breakage of capsules during carrying them.
In view of the foregoing, the present invention has been made, and a first object of the present invention is to provide a weight selecting apparatus capable of automatically performing calibration, that is, eliminating the necessity of performing the burdensome calibrating operation by manual work, thereby effectively performing high accurate, high reliable weight measurement.
A second object of the present invention is to provide a weight selecting apparatus capable of certainly carrying objects to be inspected with a relatively simple mechanism, measuring weights of the objects, and certainly ejecting the objects after weight measurement.
To achieve the first object, according to a first invention, there is provided a weight selecting apparatus including: a feed unit for continuously feeding objects to be inspected; a first weighing unit for measuring weights of the objects; a carrying means for carrying the objects fed from the feed unit to the first weighing unit one by one; an acceptability determining unit for comparing the result of weight measurement by the first weighing unit with a specific reference value to determine the acceptability of each of the objects; a selecting means for selecting the objects into non-defective ones each having a weight being within a specific weight range and defective ones each having a weight being out of the specific weight range on the basis of the determined results by the acceptability determining unit; a sampling means for performing sampling for the objects having been subjected to weight measurement by the first weighing unit; a second weighing unit for calibration, which is adapted to measure weights of those of the objects sampled by the sampling means; and a calibration unit for comparing, for the same object, the result of weight measurement by the first weighing unit with the result of weight measurement by the second weighing unit and determining whether or not a difference therebetween is within a specific error range; wherein in a usual state, the objects continuously fed from the feed unit are carried to the first weighing unit one by one by the carrying means and are subjected to weight measurement by the first weighing unit, being subjected to acceptability determination on the basis of the measured results by the acceptability determining unit, and are selected into non-defective ones and defective ones on the basis of the determined results by the selecting means and are recovered; and at specific intervals, the objects having been subjected to weight measurement by the first weighing unit are subjected to sampling by the sampling means; those of the objects thus sampled are subjected to weight measurement by the second weighing unit; and for the same object, the measured result is compared with that obtained by the first weighing unit by means of the calibration unit, to perform calibration of the first weighing unit.
That is to say, in the weight selecting apparatus of the present invention, the objects having been subjected to weight measurement by the first weighing unit are subjected to sampling by the sampling means, and those of the objects thus sampled are subjected to weight measurement by the second weighing unit. Then, the calibration unit compares, for the same object, the measured result with that obtained by the first weighing unit and discriminates whether or not a difference therebetween is within a specific error range, to thus perform calibration of the first weighing unit by making use of the objects to be inspected without use of a reference weight.
Accordingly, it is possible to automatically perform calibration by starting the sampling means, second weighing unit, and calibration unit at specific intervals arbitrarily set.
In the weight selecting apparatus of the present invention, while not exclusively, the above selecting means may include an ejecting chute for ejecting the objects having been subjected to weight measurement by the first weighing unit; a defective ejecting chute, branched from the ejecting chute, for introducing the objects to reversely rotatable non-defective recovering/carrying device; and a non-defective/defective selecting shutter, provided at the branch point where the defective ejecting chute is branched from the ejecting chute, for opening/closing a port of the defective ejecting chute; wherein the defective ejecting chute, non-defective/defective selecting shutter, and defective recovering/carrying device of the selecting means are used as the sampling means upon calibration.
That is to say, in a usual state, the non-defective/defective selecting shutter is opened/closed on the basis of the determined results obtained by the acceptability determining unit, and the non-defective objects are ejected through the ejecting chute to be recovered and the defective objects are introduced to the defective recovering/carrying device through the defective ejecting chute which is branched from the ejecting chute by opening the non-defective/defective selecting shutter and are recovered, to thereby select the objects into nondefective ones and defective ones and recover them. On the other hand, upon calibration, the non-defective/defective selecting shutter is unconditionally opened to introduce the objects having being subjected to weight measurement by the first weighing unit to the defective recovering/carrying device through the defective ejecting chute, and the defective recovering/carrying device is reversely rotated to carry the objects to in the direction different from the carrying direction upon usual defective recovery, that is, to feed the objects to the second weighing unit, whereby the objects are subjected to sampling for calibration.
Since the sample means is configured using the selecting means as described above, it is possible to certainly perform sampling for calibration with a relatively simple mechanism without provision of any complicated path, and hence to miniaturize the apparatus and reduce the parts cost. Further, since the usual weight measurement or inspection cannot be naturally performed until the accuracy of the first weighing unit is confirmed, the inspection efficiency is not reduced even by performing sampling for calibration by making use of the selecting means.
In the case where the selecting means is comprised of the ejecting chute, defective ejecting chute, and non-defective/defective selecting shutter, preferably, a defective ejection sensor for detecting passing of the objects is mounted on the defective ejecting chute or in the vicinity of an ejection port thereof, and a reversely rotatable non-defective recovering/carrying device for recovering non-defective ones of the objects is disposed ahead of the ejecting chute, wherein ejection of the object determined as a defective one by the acceptability determining unit is detected by the defective ejection sensor, and in the case where the defective object is not detected, the non-defective recovering/carrying device is reversely rotated to prevent entrainment of the defective object in the non-defective objects. This makes it possible to certainly prevent entrainment of a defective object into non-defective objects, and hence to perform weight inspection with a high reliability.
As described above, according to the weight selecting apparatus of the present invention, it is possible to automatically perform calibration, that is, eliminate the necessity of performing burdensome calibrating operation by manual works, and hence to reduce a labor required for monitoring or calibrating work by an operator and also effectively perform high accurate, high reliable weight inspection.
To achieve the above second object, according to a second invention, there is provided a weight selecting apparatus including: a feed unit for continuously feeding objects to be inspected; a weighing unit for measuring weights of the objects; a carrying means for carrying the objects fed from the feed unit to the weighing unit one by one; an acceptability determining unit for comparing the result of weight measurement by the weighing unit with a specific reference value to determine the acceptability of each of the objects; and a selecting means for selecting the objects into non-defective ones each having a weight being within a specific weight range and defective ones each having a weight being out of the specific weight range on the basis of the determined results by the acceptability determining unit; wherein the objects continuously fed from the feed unit are carried to the weighing unit one by one by means of the carrying means and subjected to weight measurement by the weighing unit, being subjected to acceptability determination on the measured results by the acceptability determining unit, and are selected into non-defective ones and defective ones on the basis of the determined results by the selecting means and are recovered; characterized in that the carrying means includes at least one intermittently rotatable carrying roller having in its outer peripheral surface portion a plurality of carrying pockets for containing the objects, wherein the objects are contained in the carrying pockets on a one-to-one basis and carried by intermittent rotation of the carrying roller; each of the objects is placed on a weighing base of the weighing unit at the lowermost point of the carrying roller in a state being contained in the corresponding one of the carrying pockets, being subjected to weight measurement in a period in which the carrying roller is left as intermittently stopped, and is moved from the weighing base by intermittent rotation of the carrying roller; and the object thus measured in weight is ejected from the carrying pocket and is transferred to the selecting means.
That is to say, the above weight selecting apparatus is configured such that as the carrying means for carrying objects to be inspected to the weighing unit one by one, there is used at least one carrying roller having a plurality of carrying pockets for containing the objects, wherein the objects fed from the feed unit are carried to the weighing base of the weighing unit by intermittent rotation of the carrying roller, being subjected to weight measurement, and are fed to the selecting means by intermittent rotation of the carrying roller. Accordingly, by provision of at least one carrying roller, objects to be inspected can be carried sequentially from the feed unit to the weighing base and to the selecting means, so that the carrying unit capable of certainly carrying the objects can be constituted of a reduced number of parts. Since the carrying unit may have at least one carrying roller as a simply movable part, that is, intermittently rotated part, it is possible to eliminate the necessity of provision of a complicated drive mechanism or control mechanism.
Consequently, according to the weight selecting apparatus of the present invention, as compared with the above-described related art weight selecting apparatus in which objects to be inspected are carried by controlling a number of movable parts requiring complicated motions with timings adjusted accurately, it is possible to accurately, certainly carry objects to be inspected by a simple mechanism with a reduced number of parts, and hence to improve the processing ability and reduce the cost.
In addition, the carrying means of the weight selecting apparatus uses the intermittently rotated carrying roller as a member for placing objects to be inspected on the weighing base one by one and moving them to the selecting means after weight measurement, and depending on the kind/feature of the objects and the specification of the feed unit for feeding the objects, the carrying means may be comprised of a combination of the carrying roller and another member. For example, like a first embodiment to be described later, the carrying unit can be comprised of a combination of the carrying roller and a feed drum for certainly charging the objects continuously fed from the feed unit into carrying pockets formed in the carrying roller, or like a second embodiment to be described later, it can be comprised of a combination of the carrying roller and a vibration feeder for sequentially feeding the objects into the carrying pockets of the carrying roller by vibration.
The carrying means using the intermittently rotated carrying roller is, of course, suitably used as the carrying means of the above-described weight selecting apparatus having the calibration function, whereby it is possible to improve the processing ability of the weight selecting apparatus having the calibration function and also to reduce the material cost and manufacturing cost.